This invention relates to improvements in printing or marking apparatus for continuously moving webs. For example, webs of sheet material are frequently continuously advanced to code, wrapping or other packaging machine which utilizes predetermined lengths, hereinafter referred to as the cut-off length, of the web. For many packaging applications, it is desirable to imprint each incremental length of material with a desired imprint, such as an identification or dating code, product identification, trademark or the like. Many such packaging machines are adapted to adjust the cut-off length of web material upon which the packaging machine operates independent of the cycle time thereof. In order to insure proper imprinting, the printing or marking apparatus must be similarly adjustable.
Further, the webs of sheet material are frequently formed from plastics or metallic foils, in which case the preferred printing or marking techniques requires the use of a heat-released pigment bearing tape pressed against the sheet material by a heated die or printing so as to transfer pigment from the tape to the sheet material, thereby forming the desired marking or imprint on the latter. Such printing or marking apparatus is generally referred to as a hot printer. In order for proper printing to be effected on a continuously moving web by means of a hot leaf printing or marking apparatus without tearing the web, the heated die must engage the web while traveling therewith at the same velocity as the web for a sufficient period of time to release the pigment from the hot leaf tape.
It is also desirable to provide a heated die of sufficient cross-sectional area so as to permit the imprinting of a substantial block of information during each imprinting. This requires the use of a substantially flat back-up member against which the heated die presses the hot leaf tape and web to insure even imprinting over a relatively large area, all of which must be accomplished while the web, heated die and back-up member are moving at substantially the same velocity.
By using the apparatus in accordance with the invention, the foregoing goals can be achieved.